An EPGS with an integrated electrical system architecture typically includes primary power distribution assemblies (PDAs) and secondary power distribution assemblies (SPDAs). Components such as generator control units (GCUs), transformer rectifier units (TRUs), contactors, circuit breakers, primary power distribution relays and circuit protection are integrated as modular assemblies within the PDAs.
The SPDAs distribute, control and protect electrical power using solid-state power controllers (SSPCs). The SPDAs are designed such that redundant microprocessors and input/output (I/O) allow them to perform utility management and remote data concentration functions as well. Both the PDAs and SPDAs are built as modular assemblies to reduce the time required removing and replacing components. In addition, each SPDA has the ability to host third party utility modules from other suppliers, or to integrate their utility functions entirely within the SPDAs embedded common hardware to perform a variety of control functions, including those of hydraulic systems, fuel systems, and air management systems. As a result, the integrated electrical system architecture has many fewer parts, fewer interfaces, shorter wiring runs, lower weight, higher maintainability, higher reliability and lower cost than non-integrated system architectures.
As indicated above, each PDA in such an EPGS integrated system architecture has an integrated TRU. The TRU serves the purpose of converting generated alternating current (AC) to direct current (DC) that is fed to a primary DC bus for transmission to at least one SPDA. Each PDA also directs the generated AC to a primary AC bus. Each SPDA then controls power to respective loads attached to the SPDA that it receives from the primary DC bus and the primary AC bus. Since the SPDAs are spread around the aircraft to be near their respective loads, the two primary busses for each PDA, AC and DC, must be spread through the aircraft as well. There would be a further savings in cost and weight as well as an improvement in reliability if only one primary bus could serve its respective SPDA. However, both AC and DC are needed by various loads throughout most aircraft.